Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a first image of a display screen or portionthereof with transitional graphical user interface, showing our newdesign;

FIG. 2 is a front view of the second image thereof;

FIG. 3 is a front view of the third image thereof;

FIG. 4 is a front view of the fourth image thereof;

FIG. 5 is a front view of the fifth image thereof; and,

FIG. 6 is a front view of the sixth image thereof.

The appearance of the transitional graphical user interface sequentiallytransitions between the images shown in FIGS. 1-6. The process or periodin which one image transitions to another forms no part of the claimeddesign.

The outer perimeter broken lines show a display screen or portionthereof and forms no part of the claimed design.

CLAIM The ornamental design for a display screen or portion thereof withtransitional graphical user interface, as shown and described.